In recent years great advancements have been made in the field of cardiac surgery. Surgical procedures to repair the heart or the heart's own blood supply are now frequently performed. One of the best known is the procedure called coronary artery bypass grafting, in which blood vessels taken from other parts of the patient's body are used to replace those portions of the coronary artery that have been damaged by disease. During such surgery it is necessary to take over the heart's function temporarily, either through a total bypass where the blood is pumped and oxygenated externally, or by the use of an intravascular blood pump.
Intravascular blood pumps are known that have a drive section integral to them, such as the one disclosed in U.S. Pat. Nos. 5,147,388 and 5,275,580. Others are intended to by powered by a remote power source via e.g. a drive shaft or cable, such as the ones disclosed in U.S. Pat. Nos. 4,625,712; 4,846,152; 4,964,864 and 5,112,349.
It is known to insert intravascular pumps into the heart through the vascular tree, via e.g. the femoral artery and the aorta. See, e.g., U.S. Pat. Nos. 4,625,712; 4,846,152 and 4,944,722. This placement suffers from the disadvantage that the aortic valve of the heart must be entered "backwards", i.e. against its natural flow direction. Great care must therefore be taken to avoid damage to the thin flaps of tissue that form the valve.
It is also known to insert intravascular blood pumps directly into the heart, piercing the heart wall at the heart's apex. See, e.g., U.S. Pat. Nos. 5,147,388; 5,275,580; 5,376,114; 5,755,784 and 5,776,190. Two problems arise with respect to the use of intravascular blood pumps that are inserted at the apex. First, such devices tend to be long and stiff, and it is difficult to maneuver the pump into position relative to the heart's internal structures. Second, the heart normally has some pressure within it, and blood tends to be forced backwards through the pump to spurt out into the open at some time during the insertion when the pump's outlet is within the heart and the pump's inlet is still outside the heart.
There has also been interest in a left atrial approach. This approach involves cutting a slit into the top of the heart into the left atrium, and threading the pump through the mitral valve into position on both sides of the aortic valve. Alternatively, this approach might involve threading the pump into the left atrium via a pulmonary vein.